Method of producing barrels of ovate section for rotary engines and the like.



H. LEE.

- METHOD OF PRODUCING BARRELS 0F OVATE SECTION FOR ROTARY ENGINES AND THE LIKE APPLICATION FILED JAN. 17, 1911.

Patented May 28, 1912.

3 SHEETS-SHEET 1.

H. LEE.

METHOD OF PRODUCING BAERELS 0F OVATE SECTION FOR ROTARY ENGINES AND THE LIKE.

APPLICATION I'ILED JAN. 17, 1911.

Patented May 28, 1912.

3 SHEETS-SHEET 2.

Invenior r Aiiorn e1 5 COLUMBIA PLANOGRAPH (IO-,WASHINGTON, D. c.

H. LEE.

METHOD OF PRODUCING BARRELS OP OVATE SECTION FOR ROTARY ENGINES AND THE LIKE.

APPLICATION FILED JAN. 17, 1911.

Patented May 28, 1912.

a SHEETS-SHEET a.

Invent/ 07" W W flilornew of the barrel.

EINETED @TATEg PATENT @FhlQE.

HERBERT LEE, OF KENSINGTON, NEAR SYDNEY, NEW SOUTH WALES, AUSTRALIA.

METHOD OF PRODUCING BARRELS OF OVATE SECTION FOR ROTARY ENGINES AND THE LIKE.

Specification of Letters Patent.

Patented May 28,1912.

Application filed January 17, 1911. Serial No. 603,111.

To all whom it may concern Be it known that I, HERBERT LEE, a subject of the King of Great Britain and Ireland, residing at Holmsdale, Bowral street, Kensington, near Sydney, in the State of New South Vales, Australia, have invented new and useful Improvements in Methods of Producing Barrels of Ovate Section for Rotary Engines and the Like, of which the following is a specification.

My invention relates to barrels of ovate section and'to the manufacture thereof for that type of rotary engines, pumps, blowers, and meters (hereinafter in this specification and in the claims thereto called engines, thereby to avoid unnecessary repetition) which consists essentially of a barrel, a drum contained eccentrically therein and rotatable in relation thereto, ports in the barrel, a piston consisting of a flat plate or vane slidable diametrally through said drum, and shoes articulated to the ends of said piston.

Heretofore rotary engines involving the elements named have been so imperfectly made, because of the reasons hereinafter stated, that only limited success'has been attained therewith. Consequently such rotary engines are in rare use, and where large dimensions are required are seldom if ever used. It has been found impossible to bore or turn internally the barrels of such engines so that the piston shoes will slide evenly upon and bear truly against the same throughout the period of rotation. No mechanical process is known by means of which the barrels of such engines can be bored or turned so as to produce a section therein which conforms exactly to that curve which the surfaces of the piston shoes describe during rotation of the drum, and it is practically impossible to plot such curve with the necessary exactness by mathematical process because the diameter of the barrel section at any point is dependent upon the angle of the shoe in relation to the piston when it is passing that point, and such angle is necessarily determined by the curve One of the known methods of production of such barrels consists in first cutting them to a roughly approximate shape, fitting the drum and shoed piston therein at one point, rotating the drum and the barrel relatively to one another, and filing and scraping the barrel in advance of the movement of the shoes to provide clearance for them. However carefully that process has heen performed, a barrel has been produced more or less unsymmetrical, or more or less irregular in curve, or more or less unparallel in the sides, or irregular in two or all three of these respects. The task of producing by such means a barrel correctly dimensioned, regularly curved, and symmetrical in section, with perfectly parallel sides, is obviously a task of infinite difiiculty and consequent prohibitive expense. Inexactness in diametral measurement as well as in the shape of the curve causes either tightness or slackness between the piston shoes and the barrel surface; where there is slackness there is necessarily leakage, and where there is tightness there is necessarily wear and heating; and when wear occurs it does not occur under such circumstances in a way which reduces the parts so as to bring them to true fit.

I am aware that there exist designs for engines and for other rotary apparatus of the crescent shape chamber and ovate barrel type, which might be mechanically effective and practically workable if a barrel could be produced having perfectly parallel sides and a section of the necessary ovate form, symmetrical, and regularly curved. The designers of such apparatus have in most cases satisfied themselves by specifying that the barrel shall be made of the necessary section to permit the revolution of the shoed piston therein, and it appears to h ave been assumed by them that such a barrel section could be produced with facility. Among the large number of such designs which are found described in the literature of the subject there may be found ovate barrels the section of which approximates to the required curve, without however in any case quite correctly conforming thereto. In the absence of any practical method of making a barrel or chamber in which the piston shoes will bear evenly and uniformly in every position of rotation, all such designs are practically useless, and even if correctly constructed in other respects could only become workable in practice when a method is known for turning or boring to the necessary section and with the necessary exactness the barrel or chamber in which the shoed piston acts. lVith knowledge of such a method the manufacture of engines of the type indicated or less serious losses are found to occur in the operation thereof, and these losses, due to leakage, friction, and excessive wear become more serious as time goes on and further wear occurs. Even with the most careful fitting work it has been found in practice that when such engines are worked at a low speed of rotation the leakage past the shoes usually becomes so great that the engine is useless, while at high speeds the wear (ultimately causing leakage) becomes'very serious and overheating occurs. It has however been proposed to form an ovate barrel by means of a copying lat-he in which the tool receives its traversing motion from a guide ring which is said to have a shape corresponding to the required interior form of the barrel. No method, however, has been described as to how this shape can be accurately produced. I have invented a mechanical process and devised apparatus for carrying out such process whereby a symmetrical ovate barrel section for any rotary engine of the kind described is determined with precision and turned accurately. By means of such process and apparatus a barrel section is produced automatically for any given engine, on the surface of which section there is perfectly even and true sliding contact of the piston shoes at every position of the piston in the barrel. I am therefore able to produce an efiicient and workable rotary engine of the type described at a low cost. My apparatus might be used if desired only for the purpose of determining the section required for the barrel of any particular engine of the type described, known methods being used for cutting such section in the barrel or in a gage or templet to" be used as a pattern in a profiling lathe or copying lathe in which the turning of the barrel is effected. But it is obviously practically necessary to turn the barrel or a gage or templet therefor in the same operation as is used to determine the section required, because the necessary exactness in the reproduction of the section is otherwise not attainable. The section obtained by my method of production is not a definite form of ovate usable with engines differently proportioned, even though the piston diameter over shoes, remains unaltered. It will vary for every engine notwithstanding that all other measurements are identical, if the dis tance between the shoe faces and the shoe articulations are different. But the geometrical form of the sections will be the same in any two apparatus of the class de scribed in which all the measurements (except axial length) are precisely identical or proportional throughout.

According to my invention, the ovate curve required in the section of a barrel for such an engine is determined and generated, and the barrel or a templet therefor is turned in a lathe provided with certain fittings, which will be hereinafter described, by means of which fittings the lathe tool is traversed during the turning operation.

In carrying out my invention, a gage, which may be integral with or attached to the barrel end, is first turned; and finally the barrel is turned. In each case the barrel is fixed on the face plate of the lathe so that the lathe axis coincides with the axial position of the drum through which the piston slides. In the first operation the horizontal component of the eccentric motion of the periphery of the barrels is applied to traverse the lathe rest during the rotation of the barrel, the cutting tool being set level with the lathe axis; by this means the tool is moved and caused to describe and out a symmetrical ovate curve which is equimetrical in all directions through the drum axis. In the second operation, the curve so described and cut is modified by using a shoe working against the said gage to traverse the slide rest to enlarge the flanks so that the section so cut will accommodate the shoed revolving piston which slides in a slot through the drum.

WVhen a barrel or a templet for a barrel has been turned to conform to a symmetrical ovate section of correct diametral dimensions for any particular engine, such barrel or templet may be used as a pattern in a profiling lathe or a copying lathe, and other barrels, replicas of the same, reproduced therein. Such replicas will obviously be usable only for apparatus in which the measurements of the parts are proportionate throughout as already stated. 7

My invention therefore includes the production of barrels of ovate section for engines of the kind described either directly by the mechanical process described, or indirectly for identical or uniformly proportionated engine by reproduction in a copying lathe or profiling machine from a templet or pattern, the original of which has been produced directly by such machine process.

Obviously the invention may be used in the manufacture of liners to be inserted in a casing or cylinder to therewith form a barrel for the purposes described.

For the purpose of making the form of the curve described and the mechanical operation before indicated fully understood, I refer to the annexed explanatory drawings, in which:

Figure l is a perspective view of a lathe provided with tool traversing fittings and having a barrel for an engine of the kind described held on the chuck or face plate thereof. This View illustrates the process of producing on a collar on the end of the barrel a gage of certain ovate form, equimetrical through the drum axis, which gage is used subsequently in the operation described with reference to Fig. 2 for traversing the slide rest during the turning of the body of the barrel. Fig. 2 is a perspective view illustrating the operation of turning the barrel after having first produced an ovate gage surface on a collar on the end thereof, against which gage surface a shoe carried by the slide rest bears for the purpose of conveying to the slide rest traversing motion, thereby moving the tool in relation to the lathe axis during the turning operation.

Fig. 3 is a fragment diagrammatic elevation showing barrel flange acting against the face of the guide plate for the purpose of converting the horizontal component of the eccentric motion of the barrel flange into reciprocating motion and applying such reciprocating motion to traverse the slide rest. Fig. 4 is a diagrammatic view of the operative elements in a profiling lathe or copying lathe in which a barrel is being turned to duplicate another'barrel or a templet for a barrel of like form and dimensions used as a pattern therein. Fig. 5 is a transverse section through the operative elements in one type of rotary engine to which the invention is applicable. This view also serves to illustrate the principle of construction of other rotary apparatus to which the invention relates. It has been inserted only for the purpose of aiding the description of the inven tion and not for the purpose of illustrating any novelty in the mechanism of the engine. Fig. 6 is an end elevation of a barrel turned interiorly according to the present invention, there being indicated on such figure a curved dotted line representing the form of the gage collar which is produced in the lathe operation described with reference to Figs. 1 and 3; and also a circle to indicate the deviation of the gage section and the barrel section therefrom.

Referring to Fig. 1, 1 is the bed of the lathe, 2 the lead screw, 3 the apron, 4 the chuck or face plate. 5 is the traversing slide which is movable laterally on the main slide 6, the mounting being of the usual dovetail form indicated at 7. A bracket 8 is mounted on the main slide 6 and a flexible cord, chain, or wire 9 attached to the traversing slide 5 runs over the pulley 10 on the end of the bracket 8. A weight 11 is attached to the end of the cord 9. Said weight 11 tends to draw the slide 5 laterally across the main slide 6. 12 is the upper slide which is mounted on the traversing slide 5 and is movable lengthwise of the bed relatively to the traversing slide 5 by means of a lead screw of the usual form which is turned by the hand crank 13. The slide 12 is mounted on the usual form of dovetail carrier 14.

15 is the tool bed which is fixed so as to be rotatably adjustable on the top of the upper slide 12. 16 is a tool holder of known type, 17 a vise or tool post in which the tool holder is held on the tool bed 15. The bed 15 is rotatable to permit ready adjustment of the position of the cutting point of the tool 18. 19 is the traversing bracket; it is secured as shown at 20 to the traversing slide 5 and carries a flat hardened guide plate 30 the face of which is set exactly perpendicular to the bed of the traversing slide 5. 21 is a barrel for an engine fixed to the chuck or face plate 4 of the lathe. The dotted line 22 indicates the horizontal plane of the chuck axis, and the dotted line 23 a diametral line parallel therewith, drawn through the center of the circular periphery of the barrel flange 24. 25 is the gage collar which is turned internally in the operation which is now to be described with reference to this figure. This gage collar after serving its purpose as a gage to traverse the lathe tool in the subsequent operation of turning the barrel, is cut off flush with the face of the flange 24, as it is thereafter no longer required. Instead of being formed integral with the barrel it may be pinned or screwed thereto temporarily and removed after the barrel has been turned. In that way a single gage ring may be made to serve in the turning of an unlimited number of barrels of the same size and section.

In all the views the barrel is shown with its lesser diameter, indicated by the diametral line 26, vertical. Upon referring to Fig. 6, it will be observed that the gage curve 94 is within the finished section of the barrel 93. This gage curve is marked 36 in Figs. 1 and 2. Both of these curves 93 and 94 lie outside a circle 104, the center of which is at the point 98 and the radius at the points 100 101. The curves 93 and 94 vanish into the circle 104 at the points 100, 101. The precise shape of the curves 93 and 94 and their diameters at various points will be different in every case according to the eccentric position of the drum axis 99, and the curve 93 will differ from the curve 94 according to the distance between the center 81 (see Fig. 5) of the articulated support of the piston shoe (see 82 Fig. 5) and the face thereof which works against the surface 72 of the barrel. The section of the finished barrel corresponds with the curve which is shown approximately and marked 93 in Fig. 6. The point 99 is the axis of the drum in which the sliding vane piston is carried and through which said piston is slidable. This point is marked 74 in Fig. 5 and it corresponds with the point marked 28 in Fig. 1. The barrel is set on the face plate of the lathe so that this point 28--99 is located on the lathe axis, in order that when the lathe is in motion and the barrel is carried around thereby, the circular periphery 91 of its flange will move as an eccentric. The dotted line 92 represents the outer surface of the body of the barrel. The diametral line 96 in Fig. 6 corresponds with the diametral line 23 in Fig. 1 and the diametral line 7 S in Fig. 5. Similarly the diametral line 97 in Fig. 6 corresponds with the diametral line 22 in Fig. 1 and the diametral line 7 9 in Fig. 5. The bracket 19 carries the guide plate 30 which must stand perpendicularly in relation to the bed of the slide rest and must be of such length that the barrel flange 24 may act against it throughout its rotation. This guide plate is therefore reciprocated transversely by the horizontal component of the vertical motion of the barrel flange and such reciprocating movement is applied to the lathe slide rest through the bracket 19. The slide rest is thus traversed once in each rotation of the lathe by a distance equal to double the eccentricity (2'. e. the distance between) of the barrel and the drum axes, the extreme positions being reached when the line (26) joining these axes lies horizontally. The face of the guide plate 30 should be hardened to resist wear which would otherwise be caused by the rubbing of the barrel flange against it. Ohviously it would be possible to produce the same traversing movement of the slide 6 by mechanism other than that described, as the horizontal component of an eccentric mo tion may be obtained by a variety of known mechanical motions. I have, however, described mechanism for obtaining the required traversing movement which appears to me to be the simplest for that purpose.

It is necessary that the cutting point of the tool 18 shall touch the barrel surface exactly where this horizontal line 28 cuts it. The position of the cutting tool 18 in relation to the barrel diameter measured on the line 26, must be adjusted neatly so that the barrel section shall be turned exactly to the proper diameter. Before the barrel is set up in the lathe as shown in Fig. 1, the flange periphery 91 must be turned circular, on the center 27.

It is not necessary that the tool 18 should be located on the side of the barrel 26 distant from the shoe 80. Precisely the same curve will be out whether the tool be used on the near side or the off side of the slide, but the necessary care must be exercised in each case to insure that the gage collar and the barrel shall be turned to the proper diameter, which is always measured between the points 100 and 101 (Fig. 6) on the diametral line 26. The points 98, 99, 100 and 101 are each readily determinable by measurement with accuracy for any barrel. When the tool is set as shown in Fig. 1, the

lathe must be rotated reversely, in which case it will of course be necessary to fix the face plate or chuck to the spindle to prevent it from working loose or screwing off. The cord 9 by which the slide rest is traversed is, as shown in Fig. 1, carried over the pulley 10, which pulley is supported on a bracket 8 which is attached to the bed of the rest 6. A coiled spring in tension, the lower end of which is attached to any fixture, may be substituted for the weight 11. As shown in Fig. 2, the bracket 8, instead of being fixed on the main slide 6, is replaced by a sheave 87 attached to a fixture independent of the lathe. In all these cases the efiect on the traversing slide rest 5 is the same, that is to say a Weight 11 or a spring acting thereon traverses the slide rest 5 across the bed rest 6, keeping the contact plate pressed against the periphery of the circular flange 24: and thus causing to be applied to the slide rest a traversing movement derived from and exactly equal to the horizontal component of the eccentric motion of the barrel axis in relation to the lathe axis.

For the weight 11 used for traversing the slide 5, there may be substituted a traverse guide precisely identical wit-h the parts 19 and 30 shown in Figs. 1 and 3. This second traversing guide is fixed to the other side of the slide 5, and bears against the periphery of the flange 24 which in that case revolves as an eccentric about the axis 28-99 between the opposed parallel faces of the guides 30, which together form in effect a parallel side yoke to which the revolving flange applies a reciprocating motion which motion is applied through the brackets 19 to the traversing slide 5.

The process herein described for generating and turning an equimetrical ovate may be used only when the distance between the eccentric axis 2899 and the closest point 101 in the ovate is at least equal to the eccentric distance 98 to 99.

The operation of turning the gage curve which is represented by the dotted line 94. (Fig. 6) and 36 (Figs. 1 and 2) is as follows, the description referring to Figs. 1 and 3:The barrel 21 is fixed on the face plate 4: of the lathe so that thepoint 28, which will be the location of the eccentric drum axis therein, will be precisely on the lathe axis. Then the measurement 100 to 101, being the least diameter of the barrel at which all the curves converge together as shown in Fig. 6 is pricked off, leaving the distance 99-101 (Fig. 6) sufiicient to permit the insertion of the drum within the barrel. The tool 18 is now set so that when the barrel is rotated the tool will neatly cut the two points 100 and 101. Firstly roughing cuts to a smaller diameter, and finally a finishing cut to exact diameter is made. As the barrel is rotated, the fiat guide plate 30 is kept by the weight 11 or equivalent device in sliding contact against the periphery 91 of the barrel flange. As the periphery (91) of the flange 24 acts upon the guide plate 30 as an eccentric, a traverse motion is applied to the slide 6 thereby and the tool 18 is traversed in relation to the lathe axis 28. The tool is fed by operating the upper lead screw by means of the hand crank 13. The curve 94 (Fig. 6), which is equimetrical through the point 99, is thus obtained, this being the curve required for the gage collar which is used subsequently to control the movements of the lathe tool during the second part of the operation in which the barrel is turned. This gage curve is shown in Fig. 2 as having been cut in the collar 25, the curve being indicated at 36.

The section turned in the gage collar by the method and apparatus just described, is constant that is to say its geometrical properties are always the same whatever the diameter may be. It is a symmetrical ovate, equimetrical at all angles through the axis 28 (99 in Fig. 6) on which it is turned, and it would therefore permit revolution in it of a sliding piston. having sharp ends. Such a piston cannot however be used in practice; it is necessary that the piston used has articulated on its ends shoes adapted to make a surface contact with the walls of the barrel, whereby sliding without excessive friction or wear is made possible and leakage is effectually prevented. WVhen such shoes are fitted to the piston ends, it becomes no longer possible to move the piston around in the barrel, as the canting of the shoes, as indicated in Fig. 5, increases proportionately the clearance required, measured over shoes, except at the points 100 and 101 where the shoes set squarely on the piston ends, and the section must therefore be modified to provide this additional clearance at all points between the fixed diametral points 100-101. The lathe is now set up to enlarge the barrel in that way, thereby to produce the modified ovate section indicated by the curve 93. In this operation the barrel is retained in the position in which the operation already described was performed. The traversing weight 11 or a substitute spring is used as before. Instead of the bracket 19, a bracket 38 (Fig. '2) is fitted on that side of the traversing rest 5 to which the traversing cord 9 is attached. This bracket 38 carries a shoe 39, the face of which is precisely identical with the face of the piston shoe to be used in the engine for which the barrel is being turned, as for instance, the shoes 82 in the case of the engine shown in Fig. 5. This shoe 39 is articulated on the end of the bracket 38. The center 41 of this rocking support 40 must be located from the face of the shoe exactly the same distance as the centers of the articulation on the end of the piston are apart from the shoe face. That is to say if in any particular case (as in the case of the engine shown in Fig. 5) the distance between the face of the shoe 82 and the center 81 about which said shoe may rock relatively to the piston 80, is one inch, then, in turning the barrel, the center 41 of the articulation 40 on the end of the bracket 38 must be pre cisely one inch from the face of the shoe 39. Moreover the bracket 38 must be so set up that the horizontal line 22 which passes through the lathe axis cuts the center 41 of the shoe articulation. Similarly also the 'cutting point of the tool 43 (which is carried in the holder 42) must be on a level of the line 22, so that a horizontal line joining the tool point and the shoe articulation center 41 will pass through the lathe axis (28, Figs. 1 and 3). The lathe tool 43 is set when the diametral line 26 coincides with the line 22, in which position the shoe 39 will lie squarely against the gage curve at the point 100 or the point 101 (Fig. 6) as the case may be, the tool point being then set at the opposite of those points 100 or 101 as the case may be. These points 100 and 101 are the only points in the ovate curve determined by measurement. The curves between them are determined by the lathe vmovements automatically. As the barrel 21 is rotated by the face plate 4 of the lathe, the tool 43 may be fed by turning the upper lead screw by means of the hand crank 13. As in the operation of turning the gage collar, first one or more roughing cuts and finally a finishing cut should be made. The shoe 39 bears throughout the operation on the gage curve 36, which is the curve 94 shown in Fig. 6. The section cut by the lathe tool, 43 under those circumstances is the perfect ovate curve 93 in which is as sured true working of a sliding shoed piston which has a diameter over shoes equal to the distance 100 to 101 and is slidable diametrally through a drum having its axis located at 99, and has its shoe articulations distant from the shoe surfaces by the same measure ment as the articulations 41 of the shoe 39 is distant from the face of said shoe.

Upon reference to Fig. 6 it. will be observed that the curves of the barrel section are shorter in radius (and the diameters therefore greater) about the parts marked 102 and 103 than at the diametral points 100 and 101. The faces of the shoes must be formed with regard to this difference in radius of the curve of the wall against which such shoes work. The shoes should be formed on their face to that radius which conforms to the shortest radius in the curve 93, that is to the radius of the said curve 93 about the positions 102103. Obviously a shoe made to conform to that curve would be liable to rock on the flatter portions of the curve in the location of the points 100101. To prevent any tendency to rock in this manner and to insure pressure tightness, spring back packing bars 87 of known type are used. It will be seen therefore that the process of determining and cutting the ovate section is entirely automatic, the lathe being set up having regard to the diametral and other measurements already particularized for each case. With my apparatus, therefore, the section of barrel required under any particular set of circumstances is determined and cut automatically with unerring exactness. The section of an engine, Fig. 5, is shown only for the purpose of indicating the class of apparatus in connection with which my invention is usable, and to make clearer the description of the operation of producing the necessary barrel section. I am aware that this particular design of engine presents no features of novelty excepting only as to the curve 7 2 of the section of the barrel, which as already explained is a curve for the first time by this inventionascertained and produced with accuracy. My invention is not limited to the construction of a barrel for an apparatus of this design solely; it will be usable in connection with any rotary apparatus whether engine, blower, pump, or-meter in which the same general relationship between the barrel, the drum, the sliding vane piston and the piston shoes is maintained, quite irrespectively of the particular form of the packing (such as 88) which is used to make a pressure tight line of contact between the periphery of the drum 7 3 and the internal surface 72 of the barrel at the point of contact 77. In this particular form of engine, which is reversible 83 and 84 are steam inlet ports, and 85 and 86 are eduction ports. 87 are packing bars in the shoes 82, and 7 6 are piston packing bars in the drum.

The face of the shoe 39 (Fig. 2) must conform exactly to the face of the piston shoe which is to be used in the engine for which the barrel is being turned, as for'instance the shoes 82 in the apparatus shown in Fig. 5, and the face of the shoe 39 must be armed with similar spring back packing pieces. These packing pieces are not shown in Fig. 2. While the middle portion of the shoe surface runs on the curve 94 (Fig. 6), during the operation of turning the curve 93, these packing bars have the effect of keeping the shoe in proper angular relation to that curve (94) by preventing it from tumbling one way or the other about its articulation 41, which it would otherwise be likely to do to some extent as its face is formed to the radius about 102103, which is a shorter radius than any part of the curve 94.

If these precautions be not observed the necessary exactness of the section 93 will not be produced, however nearly it may be approximated to. of apparatus necessarily depends upon the precise correctness of the section of the barrel, and it is therefore important that the precautions described shall be carefully observed.

Referring to Fig. 4, which explains the operation of producing a barrel from a templet ring, 64 is the face plate of a lathe, on which the barrel to be turned is fixed with the center of its flange periphery 68 concentric with the lathe axis. is a face plate carried on an axis parallel with the lathe axis. On this face plate the templet 66 is fixed with the center of its circular periphery concentric with the axis thereof. 67 is the internal surface of the templet 66. This internal section 67 is the section required to be copied in the barrel 68. The face plates 64 and 65 are geared together through toothed wheels represented by the dotted lines 61 and 63, both of which mesh with the pinion 62 the axis of which is parallelwith the axis of the two face plates 64 and 65. 50 is the bed of a lathe, 51 a traversing slide therein, similar to the slide 5 shown in preceding figures. 56 is the upper rest bearing the tool post 57 in which the tool holder 58 carrying the tool 59 is clamped. The weight 54, carried by a cord 53 working over a pulley 69 on a bracket 52 on the rest bed 50, acts upon the traversing slide 51 so as to keep the tool 59 up to its work. A tracker rod 55 bolted to the traversing slide 51 carries on its outer end a shoe 34, which is made precisely the same as the shoe 39 (Fig. 2), articulated to. it by a horizontal pin 60; the center of the pin 60 is on the line which oins the centers of the face plates 64 and 65.

The operation is as follows :-The face plate 64, being set in motion, conveys motion in the same direction and at the same speed to the face plate 65; the weight 54 holds the slide rest 51 so that the shoe 34 runs on the interior surface 67 of the templet 66. As this templet 66 rotates, it acts on the shoe 34 reciprocating thereby the slide 51 in opposition to the pull of the weight 54. By this reciprocation the tool 59 is traversed The successful operation while the barrel 68 is rotating; consequently the interior surface of the barrel 68 is turned so as to exactly reproduce therein the section 67 of the templet. This is the simplest form of a rofilin lathe for re roducin b b What I claim as my invention and desire to secure by Letters Patent is 1. The method of producing an internal surface of ovate section in a barrel for a rotary engine, of the type herein described, which method consists in fixing said barrel on the chuck of a lathe so that the eccentric drum axis will coincide with the lathe axis; traversing the slide rest which carries the tool during the rotation of the barrel by applying to it the horizontal component of the eccentric motion of the barrel whereby an ovate gage collar is turned in the end of said barrel; and then turning the barrel interiorly by rotating it while the slide rest which carries the tool at lathe center level is traversed by means of a rocking shoe bearing against said ovate gage collar also at lathe center level, but on the opposite side thereof, which shoe is identical with the piston shoe and is pivotally carried on a bracket fixed on said slide; and maintaining pressure on such slide so as to hold said shoe in sliding contact with said gage collar.

2. The method of producing a symmetrical equimetrical ovate internal surface in a gage for traversing the lathe rest in the herein described operation of turning a barrel of ovate section for a'rotary engine of the type described, which method consists in fixing said barrel or a ring of like diameter eccentrically in the chuck of a lathe so that the position of the eccentric drum axis will coincide with the lathe axis, and traversing the turning tool (which is set at lathe axis level) during the rotation of said barrel or blank by laterally reciprocating the slide rest of the lathe by mechanism which applies to it the horizontal component of the eccentric motion of the barrel.

8. The method of producing an internal surface of ovate section in a barrel for a rotary engine of the type describcd,--which method consists in fixing a circular templet eccentrically in the chuck of a lathe, firstly turning an ovate gage collar therein by 1'0- tating said chuck and traversing the slide rest by means of mechanism which applies to it the horizontal component of the eccentric motion of the barrel; subsequently turning in the templet a section conforming to the required ovate curve by rotating it while the slide rest is traversed by means of a shoe which is identical with the piston shoe and is articulated to a rocker which is fixed on the rear side or" said slide said shoe being made to bear against said gage collar; and finally, turning the required barrel in a profiling machine or copying lat-he in which the said templet is used as a pattern.

In testimony whereof I have hereunto atfixed my signature in presence of two subscribing witnesses.

HERBERT LEE.

Witnesses:

M. J. CANDRICK, V. J. DAVIS.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G. 

